bubble_chart Overview

The subcutaneous prominence at the posterior aspect of the proximal ulna is the olecranon. Together with the anterior coronoid process of the ulna, it forms the trochlear notch. This notch articulates precisely with the trochlea of the humerus. The ulnohumeral joint only allows flexion and extension movements. An ulna olecranon fracture is an intra-articular fracture involving the trochlear notch. Therefore, anatomical reduction is an effective measure to prevent joint instability and the occurrence of osteoarthritis and other complications. Ulna olecranon fractures are relatively common and mostly occur in adults, accounting for 1.17% of all fractures in the body.

bubble_chart Pathogenesis

Indirect force. When falling, the elbow joint is in an extended position, and the force is transmitted to the elbow, causing an avulsion fracture due to the pull of the triceps brachii. The fracture line may be transverse or oblique. The fracture ends are separated.

Direct force. When falling with the elbow joint extended and landing directly, or due to a direct blow to the back of the elbow, a comminuted fracture occurs, with little to no separation of the fracture ends.

There is no universally accepted classification for fractures. Beijing Jishuitan Hospital categorizes fractures into the following types.

(1) Non-displaced fracture. The fracture is not displaced and may include comminuted, transverse, or oblique fractures. X-rays show a fracture separation of less than 2 mm, and the elbow joint retains the ability to resist gravity, indicating intact elbow extension function.

(2) Displaced fracture. The fracture ends are separated by more than 3 mm, and there is no ability to resist gravity during elbow extension. This can be further divided into the following subtypes.

1. Avulsion fracture. Often occurs at the insertion point of the triceps tendon. The fracture fragment is small, and the fracture line is mostly transverse.

2. Transverse or oblique fracture. The oblique fracture line usually runs from anterior to superior (to be decocted later), which is favorable for screw fixation.

3. Comminuted fracture. Mostly caused by direct force and sometimes accompanied by open soft tissue injuries.

4. Fracture combined with elbow dislocation. Commonly seen in anterior elbow dislocations. The fracture line is transverse or short oblique and often occurs at the level of the coronoid process of the ulna with significant displacement.

bubble_chart Clinical Manifestations

After a non-displaced fracture, swelling and tenderness occur. For displaced fractures and fractures combined with dislocation, the swelling is more extensive. Zhouhou Fang A depression, fracture fragments, and bone crepitus can be palpated. Elbow joint function is lost. Most cases are easily diagnosed, but for suspicious cases, the following measures should be taken:

1. X-ray lateral view of the elbow joint—non-displaced fractures often do not show up on the anteroposterior view.

2. Bilateral X-ray comparison—before fusion, the ossification centers of the elbow joint may be confused with fractures; for suspicious cases, a comparison with the healthy side should be performed.

bubble_chart Treatment Measures

The treatment outcome of any therapeutic method should achieve strong and stable elbow extension, a good range of flexion and extension, and well-aligned articular surfaces. Common treatment methods are as follows.

1. Functional immobilization: For all types of non-displaced fractures, immobilize with a cast in full or semi-extension for 3 weeks, followed by active elbow mobilization after removal of the immobilization.

2. Open reduction and internal fixation: Displaced transverse or oblique fractures should preferably undergo open reduction. Various internal fixation methods are available, chosen based on the fracture type. Cancellous bone screws or bicortical screws are commonly used. Due to satisfactory reduction and stable fixation, elbow mobilization can begin 1–2 weeks postoperatively. Hook plates or tension band wiring with a figure-of-8 suture fixation are suitable for comminuted fractures, allowing early mobilization without external fixation.

3. Fracture fragment excision and triceps tendon reconstruction: For severely comminuted fractures where the coronoid process and distal semilunar notch remain intact, fracture fragment excision may be performed. However, a layer of cortical bone should be preserved at the triceps tendon insertion to facilitate suturing to the distal fracture surface. If cortical bone cannot be preserved, the triceps tendon can be turned down and fixed into drill holes in the distal fragment.

For cases involving open reduction or fracture fragment excision, immobilization is generally maintained in elbow extension for a short duration (about 3–4 weeks). External fixation should then be removed to allow active flexion and extension exercises of the elbow joint.